This invention relates to novel hydrocarbonaceous resins in which the starting hydrocarbon fraction, C.sub.5, employed is enriched with cis-piperylene and also to a method for their preparation and also to means adapted for such preparation.
It is known that it is possible to obtain hydrocarbonaceous fractions of a composition which varies according to the operative conditions of the steam-cracker in petroleum crushing processes. One of such fractions is composed of C.sub.5 hydrocarbons and it is known that such fraction can be used as such, or also after treatments such as dimerization, fractionation and the like, in the preparation of hydrocarbonaceous resins by employing Friedel-Crafts catalysts. Such C.sub.5 hydrocarbon fraction contains diolefines such as isoprene, piperylene and mono-cyclopentadiene, olefines such as 2-methyl-1-butene, 2-methyl-2-butene, pentenes, cyclopentene and saturated hydrocarbons such as cyclopentane, nor.pentane and others.
The percentage of these components in the fraction varies, of course, according to the type of charge present in the steam-cracker and the more or less drastic cracking conditions.
A first object of the present invention is to employ the C.sub.5 fraction in the preparation of the hydrocarbonaceous resins, the characteristic of which, as mentioned above, is a high content of cis-piperylene. This fraction is obtained by subjecting the C.sub.5 hydrocarbon fraction to a particular treatment which is an integral part of the present invention and of which an exemplary diagram is given in order to make the several steps of the same clearly understood. In the drawing accompanying the present specification the block-diagram shows the several steps to be followed in order to obtain the C.sub.5 fraction mentioned above. In the diagram a suggestion is also given as to the subsequent polymerization reaction. By so doing, however it is not intended, as is obvious, that the final formation of the resin is bound to the method followed for the production of the starting composition. On the contrary, the polymerization reaction can be performed irrespective of the origin of the composition employed, provided that it has a high content of cis piperylene.
The purpose of the accompanying drawing is to illustrate the method of the invention including the preliminary preparation of the C.sub.5 fraction of interest, it being reiterated that such preparation can be effected according to any procedure which is considered appropriate by a skilled technician.
Referring now to the diagram shown in the drawing, the hydrocarbonaceous fraction 1, exiting the steam-cracker, is fed to a dimerizer A, in which monocyclopentadiene (CPD) is converted into its dimer, dicyclopentadiene (DCP).
At the exit from the dimerizer A, the average composition of the hydrocarbon fraction C.sub.5, 2, is comprised of the following constituents in the stated ranges:
______________________________________ % by wt ______________________________________ Isoprene 15-23 Piperylene-trans 9.5-10.5 Piperylene-cis 5-6.5 CPD 0.5-1.0 DCP 15-20 ______________________________________
The balance is saturated hydrocarbons and C.sub.5 olefines.
The fraction, 2, is sent to two distillation columns, B and B', in which separation by rectification is effected in B for the lighter components, and in B' for the heavier ones, such as the piperylenes and DCP. The fraction, 3, which is enriched with isoprene, is sent to isoprene recovery at B" by following the procedures disclosed in the U.S. Pat. No. 3,851,010 assigned to SNAMPROGETTI SpA and in the article by A. Ginnasi, G. Paret and C. Rescalli, "The Recovery of isoprene from pyrolysis gasoline", presented at the Symposium on Olefine Production, Bratislava, 4 to 9 September 1972.
The tail hydrocarbon fraction, 4, of the column B' has an average composition comprised of the following constituents in the stated ranges:
______________________________________ % by wt ______________________________________ Isoprene 0.4-4 Piperylene-trans 19.5-23.5 Piperylene-cis 12.5-15.0 CPD 04-1.0 DCP 34.5-45.5 ______________________________________
The balance is saturated hydrocarbons and C.sub.5 olefines.
The fraction, 4, is then sent to the rectification column C, from the bottom of which the heavier fraction, 5 is separated, which contains DCP in a percentage of 85% and over.
The head fraction, 6, of the column C contains a high percentages of piperylenes and its composition varies within the following ranges:
______________________________________ % by wt ______________________________________ Isoprene 1-6 Piperylene-trans & cis 40-70 CPD 0.8-1.5 DCP less than 0.5 ______________________________________
The balance is saturated hydrocarbons and C.sub.5 olefines.
Such fraction, 6, is subsequently added to butadiene, 7, and the mixture is sent to the polymerization reaction for copolymerization to butadiene-piperylene(trans), D, for example, by using the procedures disclosed in A. Carbonaro, V. Zamboni, G. Novajra, G. Dall'Asta, Rubb. Chem. & Technol., 46, 1274 (1973). According to what has been reported in that paper, the butadiene-piperylene-trans copolymer, 8, is obtained in a yield of over 80% referred to the starting piperylene-trans, whereas the cis-isomer remains unaltered. On completion of the copolymerization run, after the separation of the polymer, 8, and the recovery of the unreacted butadiene and the reaction solvent, a hydrocarbonaceous fraction C.sub.5 is obtained, which is enriched with piperylene-cis, 9, and it is this fraction which is the raw material for the preparation of hydrocarbonaceous resins according to the present invention. A typical but nonlimiting composition of the fraction 9 is as follows:
______________________________________ Isoprene 7% by wt Piperylene 9 Piperylene-cis 22 DCP less than 0.1 ______________________________________
the remainder being saturated hydrocarbons and C.sub.5 olefines.
The percentages of the several components of the fractions vary, at any rate, not only as a function of the feed in the copolymerization stage, but also as a function of the operating conditions of the polymerization reaction itself.
The fraction 9, is then sent to the resin-formation step E which is carried out in the presence of cationic catalysts, examples of which will be given hereinafter.
It is also known in the patent literature that it is possible to vary the softening point of the C.sub.5 hydrocarbonaceous resins by adding to the starting C.sub.5 fraction other hydrocarbonaceous fractions or pure monomers or mixtures of pure monomers.
The objective is to obtain products which have physicochemical properties which cover a wide field of application in the adhesive range.
In this connection, it has been observed by the Applicants that it is possible, starting from the hydrocarbonaceous fraction 9 mentioned above, and by addition thereto of cyclic monomers such as dicyclopentadiene (DCP), 4-vinyl-1-cyclohexene (VCE), styrene or its derivatives or C.sub.8 -C.sub.9 hydrocarbonaceous fractions, to obtain, by polymerization, resins having a softening point which is higher than that exhibits by the resins which can be obtained from the 9 fraction as such.
As a matter of fact, when operating with all the other conditions being the same but with percentages of such monomers varying between 20% and 120% by weight relative to the hydrocarbonaceous fraction 9, resins are obtained, which have a softening point, on an average, above 90.degree. C. On the other hand, by adding to the fraction 9 in the same ratios indicated above, oligomers obtained by polymerizing propylene to trimers, tetramers, pentamers or hydrocarbon fractions C.sub.4 stripped of butadiene, there are obtained products which have a lower softening point which is below 50.degree. C. and under certain conditions below room temperature.